Brief overview of the paper and its main findings

The authors of this review investigated various technologies integrated with MFC to eliminate the limitation of typical standalone MFC technology. This work belongs to an important and emerging research field and the scope of this paper is suitable for Applied Science. The topic of this paper has been very popular recently and is expected to receive attention from readers. However, there are some issues in this paper that need to be resolved to improve the quality of this paper.

Major and minor points

1)For Section 3 (Lifecycle Assessment (LCA) of integrated Microbial Electrochemical Systems), since there is only one related study about the MFC-FO, this section needs to be merged with the second section.

2)In Section 4, the authors discussed several challenges of integrated MFC, but in fact these drawbacks of integrated MFC are also the limitations of standalone MFC. I assume that some of the integrated techniques could solve some limitations but not all. This section should be more detailed to illustrate which integrated technologies could be the solution to the challenges mentioned.

3)As mentioned above, different integrated MFCs have different directions to remove the limitations of traditional MFC. A comprehensive discussion could help readers to understand their advantages and disadvantages. For example, whether the integrated MFCs could reduce the cost? Whether the integrated MFCs are more effective to remove the contaminants or generate higher power? This could be combined with Section 4, listing a table and exhibiting if or not these integrated MFCs are in favor of solving various challenges.

4)In consideration of the arising attention to MFC, there are tremendous numbers of research and reviews in this area. Please ensure a comprehensive inclusion of up-to-date studies in this review. In my opinion, the following studies need to be included in this review: Tavakolian, M., Taleghani, H.G. and Khorshidian, M., 2020. New design of benthic microbial fuel cell for bioelectricity generation: Comparative study. International Journal of Hydrogen Energy, 45(43), pp.23533-23542. Zhang, Y., Wang, Y. and Angelidaki, I., 2015. Alternate switching between microbial fuel cell and microbial electrolysis cell operation as a new method to control H2O2 level in Bioelectro-Fenton system. Journal of Power Sources, 291, pp.108-116. Zhang, L. and Deshusses, M., 2014. Application of the finite difference method to model pH and substrate concentration in a double-chamber microbial fuel cell. Environmental technology, 35(9), pp.1064-1076.
Kim, H.W., Lee, K.S., Razzaq, A., Lee, S.H., Grimes, C.A. and In, S.I., 2018. Photocoupled bioanode: a new approach for improved microbial fuel cell performance. Energy Technology, 6(2), pp.257-262. Hernández-Fernández, F.J., de los Ríos, A.P., Mateo-Ramírez, F., Godínez, C., Lozano-Blanco, L.J., Moreno, J.I. and Tomás-Alonso, F., 2015. New application of supported ionic liquids membranes as proton exchange membranes in microbial fuel cell for waste water treatment. Chemical Engineering Journal, 279, pp.115-119.

Other minor issues are: 1)Line 95. Replace the unit “mg/l” with “ mg/L” for uniformity. 2)Line 131. Delete “are” before “remaining to resolve” 3)Line 140-141. Here I do not understand the meaning of the sentence “Economical constraint the only hindrance in their commercial application”. Maybe it could be deleted. 4)Line 167. Delete “aq.” Before “the solution”. 5)Please keep enough space between the main text and the illustration of figures for recognition.

Conflicts of interest

Do you have any conflicts of interest here?

No